Recycling an Android Phone As a Handheld GPS? 328
imblum writes "So my dad's antique handheld GPS unit just went toes up and I was considering replacing it for him with an old Android Smartphone. All he really needs it for is hunting and camping (no navigation), so I don't want to pay for cell or data service. I found the program Mobile Atlas Creator to download map files onto the SD card, and an app called Maverick Lite to view them. Now all I need is to decide on an Android phone. I was considering a Samsung Behold II ($100-200 on Craigslist), but thought it would be nice to get some input from the Slashdot community. It seems like I can get a lot more functionality for the money out of an old Android than I could from a big name handheld GPS. Does this plan sound reasonable? Is there anything I'm overlooking?"
Why? (Score:5, Informative)
You're talking about spending $100-200 on an Android phone, and you can get a real dedicated GPS receiver for $90 that requires no effort to set up, no purchase of an additional flash card, has a warranty, etc.
Used GPS are cheap (Score:5, Informative)
I just bought a used Magellan explorist 500 ion Amazon for $7. Why bother with hacking an android phone?
Cell phone GPS not the same... (Score:5, Informative)
Cell phones rarely have WAAS. Cell phones usually also use the cellular system to receive the phase of the GPS satellite transmission to aid in reception--but--if you don't have any service, the accuracy can get pretty deplorable (well, compared to say my GPSmap 60CSx that usually locks within fourteen to sixteen feet)...the battery life isn't as good, cell phones are horribly made, and the chipsets and antennae are simply much, much, much better in a dedicated unit. Pick up a used GPS--that's a real GPS--and it will be much better suited to hunting and camping rather than looking for the closest Starbucks. Real GPS units have rubber gaskets for a reason.
durability (Score:4, Informative)
Outdoor GPS more ruggedised (Score:4, Informative)
Depends on how your dad uses his GPS and what he needs to do with it, but Android smart phones aren't generally designed for rough conditions.
I've got a Garmin eTrex and an Android phone. The Garmin is way more ruggedised than the touch screen smart phone (Motorola Milestone). I don't think the Milestone would cope with pouring rain, snow, getting knocked about in rucsacs, dropped in puddles, sat on, etc, and still function in bad weather at night when I really need to know where I am: it might be life or death. "Smart phones" with a few exceptions are much too flimsy for outdoor use in severe conditions.
Hard to beat dedicated GPS (Score:1, Informative)
A phone is:
1) not going to be as durable or rain resistant
2) not going to have as good battery life (while acting as a GPS)
3) probably not going to allow you to swap out ordinary AA or AAA batteries if you do run out (most phones have dedicated chargers and batteries)
4) probably not going to be as precise
5) probably going to involve more hassle loading maps (most GPS units have basic maps already loaded).
With dedicated GPS units in same price range as the Android phones you are talking about (e.g., mapping GPS units start at $150 [garmin.com], and there are other brands, such as Magellan), the question is WHY would you get a phone if a GPS is what your dad needs? Some models even float, such as this $200 model [garmin.com], which would be great for hunting/camping. Check this place out to see the variety available [gpscity.ca]. I'm sure there's an equivalent store in the USA.
If you already have an old phone laying around, it might be worth a try. Otherwise you're probably going to regret paying almost as much for a suboptimal solution.
Re:Battery availability might be a concern. (Score:3, Informative)
Airplane mode disables all the wireless including gsm. Battery life will still likely be an issue for hunting, probably can get a few days with occasional checks.
Re:Get him a dedicated GPS device (Score:1, Informative)
Re:Cell phone GPS not the same... (Score:5, Informative)
I know you're trying to be funny, but I've been in a situation where I had to find out how worthless all the "GPS-capable" smartphones in my hiking group really were. For the discussion at hand, it doesn't matter if it's an Android, WinMo, or Apple. They're the same: absolute crap.
You're looking at a few crappy metal traces which are shared with all sorts of other radio gear compared to an actual hard-core ceramic patch antenna.
Want to see quick numbers? Let's go to sparkfun.com:
Cell phone class antenna: GPS-09131
Gain: 2.6dBi
Mini wussy GPS helical antenna: GPS-09871
Gain: 18dB (typical, they claim)
Old school generic ceramic GPS antenna: GPS-00177
Gain: 26dB
A group of us got lost in the hills hiking. Given that most phones depend on cell tower assistance for GPS, all of them couldn't tell us where we were. So after wandering into the next park's guest station, they drove us 45 minutes back to our starting location. Next time, I'm bringing an old WinMo2003 handheld with a GPS CF card because it actually has the right kind of antenna. (as well as WAAS support, etc)
Android phone as a GPS in the woods? Hell no.
Motorola Droid, not so good as GPS (Score:4, Informative)
Re:Battery availability might be a concern. (Score:3, Informative)
Re:Why? (Score:3, Informative)
A cellphone does not obtain your position using the free signal received from GPS satellites that dedicated GPS units use
Huh? My venerable G1 does exactly that, in addition to using cell-tower triangulation (my understanding is that it uses the cell tower method to provide a rapid initial location and then refines it using true GPS.) You can actually disable triangulation in the phone's configuration screen, in which case it's a pure GPS device. I'm sure there are older phones that don't have actual GPS receivers in them, but any smartphone capable of running navigation software will. GPS chips are cheap, and they're in everything nowadays. Try not to sound so authoritative when you're incorrect.
Furthermore, the lack of a data plan in no way affects the efficacy of the phone's positioning system, it simply means that you can't use a navigation product such as Google Nav or Telenav which require online access to map and routing data. There are a number of good GPS products for Android that function perfectly well without wireless access, because they work just like a dedicated unit: they store all their data in local flash memory.
Re:Cell phone GPS not the same... (Score:3, Informative)
It sounds like GPS antenna in your phone is borked in some way, or GPS controller is. I own a nokia 5800, and while accuracy leaves a lot to be desired, usually between 50m and 100m (as it should, the antenna is about a centimeter long), it exhibits none of the problems you mention. Initial lock is acquired within minutes of activation (no aGPS, no data, no wifi, internal GPS antenna only), and once it's in, driving instructions are impeccable, actually beating older tomtom standalone navigators by a very wide margin (and worlds ahead and beyond anything that android can offer at the moment afaik).
Heck, the phone warns me about speed cameras and warns me audibly if my speed is above allowed in the area as I drive. That just isn't possible in the situation you describe. Get your phone checked with local repair shop.
Re:Why? (Score:5, Informative)
Huh? You're not paying for the right to use the GPS chip, any more than you pay your carrier for the (ahem) "right" to use the audio chip.
I take it you've never been a victim...errr, customer of Verizon. My dad has them, and he actually has to pay an extra monthly fee to be able to move pictures and video from his phone to his computer. It's the craziest shit I've ever seen. I don't care if they have better coverage than T-Mobile, at least I'm on a carrier that gives me complete control over what I do with my phone.
Re:Cell phone GPS not the same... (Score:3, Informative)
Yeah. You have a fundamental misunderstanding what antenna gain means. As a passive device, an antenna can not provide "gain" in the sense you are thinking of. Antenna "gain" is merely its directivity minus its insertion loss. I do not doubt that the insertion loss may be lower on a dedicated unit. Still, "gain" is not a good thing.
Gain is approximately directivity. Directivity tells you how "pointy" your beam is. A high gain antenna will allow you to measure fainter signals, assuming you are aiming at them exactly. A "low gain" antenna has a comparable beam in all directions, meaning that you do not need to aim your device at anything in particular.
As for the actual question at hand: try a symbian phone such as the e71x, e71, Nokia Nuron, or any other recent low-cost nokia smart phone. Nokia's Ovi Maps application allows you to download entire continents of maps over your computer, and offers turn-by-turn directions. Or better yet, get a real GPS. It will cost you an extra $25, and will make your dad's life easier.
Re:Cell phone GPS not the same... (Score:3, Informative)
That's because he's looking at LNA gain on an active antenna. Oops.
I can pretty much guarantee you that those helical and ceramic patch antennas won't be much more than +3 or +4 dBi. There are only two ways to improve antenna gain: directionality and physical size. Directionality (aside from "up") is exactly what you *don't* want in a GPS antenna. You ideally need 360 degree azimuthal and 180 degree elevational coverage, and that's only if you don't plan on ever tilting the device from the horizontal plane. As for physical size, well, all of those antennas are within the same order of magnitude of compactness, so I don't expect much variation there. Yes, structural design matters, but it's a few dB of matters, not tens.
Re:You did overlook something (Score:3, Informative)
That's idiotic. Cell service is tower based. GPS is satellite based. If you have clear sky to two of the satellites, you can get a decent idea of where you are, three and you can really only be two places and it's a safe bet you're in the place closest sea level. The general idea is that GPS should be visible from anywhere. Cell towers are located close to population centers because it's cost efficient.
Re:Battery availability might be a concern. (Score:3, Informative)
Yes, the cell service assists the GPS to find a signal quicker. That doesn't mean you can't get a GPS signal if you don't have cell service. It will just take a little longer.
Re:Battery life might be a concern. (Score:5, Informative)
I did a reasonably extensive amount of research into how to do this, and I'm pretty confident I know the answer.
1. Get OruxMaps - it allows you to use maps without an active internet connection.
2. While connected to wifi, download the tiles from google terrain (or one of the other map sources available). If you know exactly where you're hiking, you can get zoomed in maps for say a 20 mile square around the center of your hike with amazing resolution.
3. Put your phone in a plastic bag, and only take it out if you actually don't know where you are (I find that I almost always do).
In terms of battery life, I was using my android phone as a camera too, and checking GPS every few hours to verify I was in the right place, and it lasted for three days taking down the battery by 40%. Make sure to turn off the cell tower seeking and such or else you will drain the battery really fast. Airplane mode probably won't allow you to receive GPS, unfortunately, but you can at least turn off wireless, data connections, etc.
If you aren't going to be gone very long, and you want a cool log of your trip, you can have OruxMaps poll the GPS in "power saving" mode, which as far as I can determine seems to mean connecting, and then dropping to low power (non-receiving) mode for 10-20 seconds before polling the satellites again. Then you can tell it to make a "track", and it will record your hike -- average speed, immediate speed at each point, speed distribution, altitude map, total distance, and other cute information.
Hopefully someone will mod this up high enough that the submitter can see it... this is the part of ask slashdot that always confuses me. Hopefully a few hundred other people came up with the same solution, so at least one of us is actually noticed =)
Re:Cell phone GPS not the same... (Score:3, Informative)
You have totally sidestepped the question. No, he wasn't looking at LNA gain on an active antenna, he was looking at a chart on a website.
PipsqueakOnAP133 appears to have been copying figures including the units (or lack of meaningfull units as I explain below) from product discritions. I don't see any evidence of a chart being involved.
Lets take a proper look at the three products he listed
GPS-09131 is a passive PCB mount antenna, a figure of 2.5dBi is given in the product description (dunno why PipsqueakOnAP133 said 2.6, maybe it was just a typo) and this seems sensible.
The other two are both active antennas so we have to determine what the gain figures listed in the product descriptions really mean. They seem highly unlikely to be an antenna gain because an antenna of that gain would be too directional* to be much use for something like GPS.
For GPS-09871 the datasheet says the gain is in a minimum of 17dBic and typically 18dBic but doesn't say how much of that gain is antenna gain and how much is LNA gain. However the polar plots given make it obvious (at least to someone with an RF background) that most of it must be LNA gain.
For GPS-00177 the datasheet says the antenna gain is 3±0.5 dB but leaves us to guess as to what reference atenna they used it also gives a LNA gain of 28±3 dB.
Repeat: is he talking about dBi or dB? Depending on which, the numbers are not going to be the same. But he mixed the two.
dB on it's own is meaningless for measuing antenna gain, antenna gain has to be measured relative to a reference antenna this can be among other things a theoretical isotropic antenna (dBi), a circularly polarised theoritical isotropic antenna (dBic) a half-wave dipole (dBd).
If someone says dB when talking about antenna gain and the couple of dB of difference between different measurements matters you need to ask them to clarify.
* Antenna gain is NOT a free lunch, gain in one direction will always come at the cost of loss in another.
Re:Battery availability might be a concern. (Score:3, Informative)
Exactly. When I read this " I was considering a Samsung Behold II ($100-200 on Craigslist)" I was starting to doubt the author had even priced GPS units since they're far below $100 now
Since "All he really needs it for is hunting and camping (no navigation)," why not get a device soley created for that purpose like a $75 Garmin eTrex. [walmart.com] High sensitivity, waterproof, and up to 17 hours on two AA batteries.
Now if author's dad wanted a Android so he could use GPS and other software I would understand not buying a dedicated GPS, but he made no mention at all of ever using it for anything other than a GPS.
Re:Battery availability might be a concern. (Score:3, Informative)
He lives (and goes hunting) in Alaska, and they don't have GPS in most of the state because of how far north it is. He could not see enough satellites to determine his position. I was stunned to think that GPS didn't work up there. I had no idea, and neither did my dad.
Nonsense, Alaska isn't far north. Most of it is on the same latitude as Finland, and we have no problems with GPS here. In fact, you can go to the north pole and have your GPS tell you you're at N 90 degrees. [yellowairplane.com] I think your dad was probably between too many mountains.
Re:Battery availability might be a concern. (Score:3, Informative)
This is incorrect.
The GPS constellation is arranged so this should be impossible unless:
Although none of the satellites are in a direct polar orbit (this avoids occasional "bunching" of satellites, a problem encountered by a forerunner to GPS called "Transit".), the constellation is divided into six orbital planes at varying inclinations. There is nowhere on the surface of the Earth where fewer than four satellites should be visible at any one time.
It is true that the lack of a direct polar plane means that in polar regions the satellites will sit lower on the horizon than in regions that are closer to the equator (They'll never be directly overhead in Alaska [colorado.edu]). But if the device is capable, and it's being used properly, you WILL be able to use it in Alaska or anywhere.
Read up in it if you're skeptical:
http://home.earthlink.net/~fjolles/gps.htm [earthlink.net]
http://www.kowoma.de/en/gps/orbits.htm [kowoma.de]
http://www.colorado.edu/geography/gcraft/notes/gps/gps_f.html [colorado.edu]